title: Effects of chain length and pH on the uptake and distribution of perfluoroalkyl substances in maize (Zea mays).
abstract: Maize is the most important grain crop grown for human nutrition, animal fodder and biogas production worldwide. Nonetheless, no systematic studies have been undertaken on these plants to examine the uptake mechanisms for perfluoroalkyl substances (PFASs) dependent upon chain length and pH value. The aim of the present study was therefore to determine the influence of chain length (C4 to C10) and pH value (pH 5, pH 6, pH 7) on the uptake and distribution of seven perfluoroalkyl carboxylic acids (PFCAs) and three perfluoroalkane sulfonic acids (PFSAs) by maize in nutrient solution experiments under controlled conditions in a climate chamber. A pH-dependent uptake was observed for perfluorodecanoic acid (PFDA) with an uptake rate of 2.51 μg g(-1) at pH 5 compared to 1.52 μg g(-1) root dry weight (DW) per day (d) at pH 7. Perfluorobutanoic acid (PFBA) had the highest uptake rate within the group of PFCAs with an average of 2.46 μg g(-1) root DWd(-1) and perfluorooctane sulfonic acid (PFOS) had the highest uptake rate (3.63 μg g(-1) root DWd(-1)) within the group of PFSAs. The shoot:root ratio for shorter-chain PFCAs (≤ C7) and PFBS (C4) was >2.0, which indicates that shorter-chain PFASs are transferred predominantly and at higher concentrations to the shoot. In contrast, long-chain PFCAs such as perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) as well as the PFASs perfluorohexane sulfonic acid (PFHxS) and perfluorooctane sulfonic acid (PFOS) accumulated at higher concentrations in the roots of maize plants with a shoot:root ratio of <1.0.
authors.affiliation: Institute of Plant Nutrition, Faculty of Agricultural Sciences, Nutritional Sciences and Environmental Management, Justus Liebig University, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany. Electronic address: johanna.krippner@ernaehrung.uni-giessen.de.
authors.forename: Johanna
authors.initials: J
authors.lastname: Krippner
authors.forename: Hubertus
authors.initials: H
authors.lastname: Brunn
authors.forename: Sandy
authors.initials: S
authors.lastname: Falk
authors.forename: Sebastian
authors.initials: S
authors.lastname: Georgii
authors.forename: Sven
authors.initials: S
authors.lastname: Schubert
authors.forename: Thorsten
authors.initials: T
authors.lastname: Stahl
mesh_terms: D017738:Alkanesulfonic Acids / Q000378:metabolism; D002210:Caprylates / Q000378:metabolism; D003652:Decanoic Acids / Q000378:metabolism; D005466:Fluorocarbons / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D012989:Soil Pollutants / Q000737:chemistry / Q000378:metabolism*; D003313:Zea mays / Q000378:metabolism*
chemical_list: D017738:Alkanesulfonic Acids; D002210:Caprylates; D003652:Decanoic Acids; D005466:Fluorocarbons; D012989:Soil Pollutants; C036567:perfluorodecanoic acid; C033094:perfluorobutyric acid; C023036:perfluorooctanoic acid; C076994:perfluorooctane sulfonic acid; C078626:perflexane
keywords: Nutrient solution experiment; Shoot:root ratio; Short-chain PFASs; pH-dependent uptake